Structural validity of the Movement ABC-2 test : factor structure comparisons across three age groups

Background: The Movement ABC test is one of the most widely used assessments in the field of Developmental Coordination Disorder (DCD). Improvements to the 2nd edition of the test (M-ABC-2) include an extension of the age range and reduction in the number of age bands as well as revision of tasks. The total test score provides a measure of motor performance, which can be used to help make a diagnosis of DCD. M-ABC-2 also provides 3 sub-scales for Manual Dexterity, Aiming and Catching and Balance but the validity of these conceptually derived sub-scales has not previously been reported. Aim: To examine the factor structure of the M-ABC-2 test across the three age bands (AB): AB1 (3-6-year olds), AB2 (7-10-year olds) and AB3 (11-16-year olds). Method: Data from the 2007 standardisation sample (N = 1172) were used in this study. Confirmatory factor analyses (CFA) and structural equation modelling (LISREL 8.8) were employed to explore the relationship between the tasks within each of the 3 age bands. A model trimming approach was used to arrive at a well fitting model. Results: In AB1 a complex factor structure emerged providing evidence for an independent general factor, as well as specific factors representing the 3 test components. In AB2 a final model emerged with four correlated factors, an additional distinction being drawn between static and dynamic balance. In addition, a 2nd order general factor explained a considerable amount of variance in each primary factor. In AB3 CFA supported the 3-factor structure of the M-ABC-2, with only modest correlations between each factor. Conclusions: The confirmatory factor analyses undertaken in this study further validate the structural validity of the M-ABC-2 as it has developed over time. Although its tasks are largely associated with the three sub-components within each age band, there was also clear evidence for a change in the factor structure towards differentiation in motor abilities with age.